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Magnetically controllable multimode interference in topological photonic crystals

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Light(science & Applications) 2024年第5期13卷 998-1005页

作者： Weiyuan Tang Mudi Wang Shaojie Ma Che Ting Chan Shuang Zhang New Cornerstone science Laboratory Department of PhysicsThe University of Hong KongHong KongChina. Department of Physics The Hong Kong University of Science and TechnologyHong KongChina. Department of Optical science and Engineering Fudan UniversityShanghai 200433China

Topological photonic insulators show promise for applications in compact integrated photonic circuits due to their ability to transport light robustly through sharp *** number of topological edge states relies on the difference between the bulk Chern numbers across the boundary,as dictated by the bulk edge *** interference among multiple topological edge modes in topological photonics systems may allow for controllable functionalities that are particularly desirable for constructing reconfigurable photonic *** this work,we demonstrate magnetically controllable multimode interference based on gyromagnetic topological photonic insulators that support two unidirectional edge modes with different *** successfully achieve controllable power splitting in experiments by engineering multimode interference with the magnetic field intensity or the frequency of *** work demonstrates that manipulating the interference among multiple chiral edge modes can facilitate the advancement of highly efficient and adaptable microwave devices.

关键词： multimode controllable microwave

Stability and Generalization of Hypergraph Collaborative Networks

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Machine Intelligence Research 2024年第1期21卷 184-196页

作者： Michael K.Ng Hanrui Wu Andy Yip Institute of Data science The University of Hong KongHong KongChina Department of Mathematics The University of Hong KongHong KongChina College of Information science and technology Jinan UniversityGuangzhou 510006China

Graph neural networks have been shown to be very effective in utilizing pairwise relationships across ***,there have been several successful proposals to generalize graph neural networks to hypergraph neural networks to exploit more com-plex *** particular,the hypergraph collaborative networks yield superior results compared to other hypergraph neural net-works for various semi-supervised learning *** collaborative network can provide high quality vertex embeddings and hyperedge embeddings together by formulating them as a joint optimization problem and by using their consistency in reconstructing the given *** this paper,we aim to establish the algorithmic stability of the core layer of the collaborative network and provide generaliz--ation *** analysis sheds light on the design of hypergraph filters in collaborative networks,for instance,how the data and hypergraph filters should be scaled to achieve uniform stability of the learning *** experimental results on real-world datasets are presented to illustrate the theory.

关键词： Hypergraphs vertices hyperedges collaborative networks graph convolutional neural networks(CNNs) stability generalization guarantees

Highly active and durable core-shell electrocatalysts for proton exchange membrane fuel cells

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Nano Research 2024年第10期17卷 8772-8784页

作者： Hsiwen Wu Fei Xiao Jing Wang Meng Gu Minhua Shao Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayHong KongChina Department of Materials science and Engineering Southern University of Science and TechnologyShenzhen 518055China Fok Ying Tung Research Institute The Hong Kong University of Science and TechnologyGuangzhou 511458China Energy Institute and Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution The Hong Kong University of Science and TechnologyClear Water BayHong KongChina

This work presents simple post-treatment methods to selectively and partially remove the Pd core of Pd-Pt core–shell(Pt@Pd/C)*** proton exchange membrane fuel cell with the post-treated Pt@Pd/C cathode(Pt loading:0.10 mg·cm^(-2))delivers an impressive peak power density of 1.2 W·cm^(-2).The partial removal of Pd core endows an ultrahigh oxygen reduction reaction(ORR)mass activity of 0.32 A·g_(PGM)-1 when normalized to the platinum group metal(PGM)mass,or equivalently 0.55 A·mg_(Pt)^(-1) at 0.9 V measured in a fuel *** post-treatment thickens the Pt shells and mitigates the Pd dissolution during potential *** a result,the post-treated core-shell catalyst demonstrates superior durability in ORR mass activity and polarization power density retention than untreated core-shell catalyst and benchmark Pt/***-situ inductively coupled plasmamass spectrometry(ICP-MS)results highlight that the amount of dissolved Pd in post-treated core–shell catalyst is 17-times lower than that of the untreated *** findings highlight the importance of structural tuning of catalysts in enhancing their mass activity and durability.

关键词： core-shell catalyst platinum monolayer proton exchange membrane fuel cell oxygen reduction reaction durability

UV-Based Advanced Oxidation Processes for Antibiotic Resistance Control: Efficiency, Influencing Factors, and Energy Consumption

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Engineering 2024年第6期37卷 27-39页

作者： Jiarui Han Wanxin Li Yun Yang Xuanwei Zhang Siyu Bao Xiangru Zhang Tong Zhang Kenneth Mei Yee Leung Department of Civil and Environment Engineering The Hong Kong University of Science and TechnologyHong Kong 999077China Department of Civil Engineering The University of Hong KongHong Kong 999077China State Key Laboratory of Marine Pollution and Department of Chemistry City University of Hong KongHong Kong 999077China

Antibiotic resistant bacteria(ARB)with antibiotic resistance genes(ARGs)can reduce or eliminate the effectiveness of antibiotics and thus threaten human *** United Nations Environment Programme considers antibiotic resistance the first of six emerging issues of *** oxidation processes(AOPs)that combine ultraviolet(UV)irradiation and chemical oxidation(primarily chlorine,hydrogen peroxide,and persulfate)have attracted increasing interest as advanced water and wastewater treatment *** integrated technologies have been reported to significantly elevate the efficiencies of ARB inactivation and ARG degradation compared with direct UV irradiation or chemical oxidation alone due to the generation of multiple reactive *** this study,the performance and underlying mechanisms of UV/chlorine,UV/hydrogen peroxide,and UV/persulfate processes for controlling ARB and ARGs were reviewed based on recent *** affecting the process-specific efficiency in controlling ARB and ARGs were discussed,including biotic factors,oxidant dose,UV fluence,pH,and water matrix *** addition,the cost-effectiveness of the UV-based AOPs was evaluated using the concept of electrical energy per *** UV/chlorine process exhibited a higher efficiency with lower energy consumption than other UV-based AOPs in the wastewater matrix,indicating its potential for ARB inactivation and ARG degradation in wastewater *** studies are required to address the trade-off between toxic byproduct formation and the energy efficiency of the UV/chlorine process in real wastewater to facilitate its optimization and application in the control of ARB and ARGs.

关键词： Advanced oxidation processes Ultraviolet/chlorine Ultraviolet/hydrogen peroxide Ultraviolet/persulfate Antibiotic resistant bacteria Antibiotic resistance genes

Hybrid vibration isolation optimization of a flexible manipulator based on neural network agent model

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Chinese Journal of Aeronautics 2024年第5期37卷 482-505页

作者： Yongxin ZHANG Liang LI Dingguo ZHANG Wei-Hsin LIAO Xian GUO School of science Nanjing University of Science and TechnologyNanjing 210094China Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

Segmented Active Constrained Layer Damping(SACLD)is an intelligent vibration-damping structure,which could be applied to the sectors of aviation,aerospace,and transportation engineering to reduce the vibration of flexible ***,machine learning technology is widely used in the engineering field because of its efficient multi-objective *** dynamic simulation of a rotational segmental flexible manipulator system is presented,in which enhanced active constrained layer damping is carried out,and the neural network model of Genetic Algorithm-Back Propagation(GA-BP)algorithm is *** suppression and structural optimization of the SACLD manipulator model are studied based on vibration mode and damping *** modal responses of the SACLD manipulator model at rest and rotation are *** addition,the four model indices are optimized using the GA-BP neural network:axial incision size,axial incision position,circumferential incision size,and circumferential incision ***,the best model for vibration suppression is obtained.

关键词： Machine learning Vibration suppression Flexible manipulator Segmented active constrained layer damping Structural optimization

Towards efficient generative AI and beyond-AI computing:New trends on ISSCC 2024 machine learning accelerators

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Journal of Semiconductors 2024年第4期45卷 12-15页

作者： Bohan Yang Jia Chen Fengbin Tu Department of Electronic and Computer Engineering The Hong Kong University of Science and TechnologyHong KongChina AI Chip Center for Emerging Smart Systems The Hong Kong University of Science and TechnologyHong KongChina School of the Gifted Young University of Science and Technology of ChinaHefei 230026Chin

Compared to the last decade when the convolution neu-ral network(CNN)dominated the research field,machine learn-ing(ML)algorithms have reached a pivotal moment called the generative artificial intelligence(AI)*** the emer-gence of large-scale foundation models[1],such as large multi-modal model(LMM)GPT-4[2]and text-to-image generative model DALL·E[3].

关键词： ISSCC beyond AI

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

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Journal of Energy Chemistry 2024年第6期93卷 289-298,I0008页

作者： Yinuo Wang Yian Wang Qinglan Zhao hongming Xu Shangqian Zhu Fei Yang Ernest P.Delmo Xiaoyi Qiu Chi Song Juhee Jang Tiehuai Li Ping Gao MDanny Gu Minhua Shao Advanced Materials Thrust The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511400GuangdongChina Department of Chemical and Biological Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Department of Materials science and Engineering Southern University of Science and Technology of Chin11088 Xueyuan BoulevardShenzhen 518055GuangdongChina Energy Institute and Chinese National Engineering Research Center for Control&Treatment of Heavy Metal PollutionThe Hong Kong University of Science and TechnologyKowloonHong KongChina Department of Chemistry City University of Hong KongTat Chee AvenueKowloonHong KongChina

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of ***,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen *** thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~**** work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

关键词： Copper carbonate hydroxide Co-reduction Urea generation C-N coupling DFT calculation

Facile synthesis of transition metal complexes with five coplanar metal-carbon σ-bonds

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National science Review 2024年第4期11卷 11-12页

作者： Guocheng Jia Department of Chemistry Hong Kong University of Science and Technology

Carbon is one of the most important elements in chemistry, forming a vast number of organic compounds. It can also form a variety of organometallic compounds with a metal–carbon bond. Metal alkyl, carbene and carbyne complexes are classical examples of organometallic compounds. A particularly interesting class of organometallic compounds are all-carbon metallacycles formed by combination of a metal and a hydrocarbon chain serving as a chelating agent with only carbon atoms as the donor atoms. Many interesting monocyclic metallacycles made of a chelating bidentate hydrocarbon chain are known, for example, metallacyclobutadienes, metallacyclopentadienes and metallabenzenes[1].

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Magnetic field regression using artificial neural networks for cold atom experiments

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Chinese Physics B 2024年第2期33卷 46-51页

作者：陈子霆黃建陶 Bojeong Seo 黄明琛 Mithilesh K.Parit 何逸飞甄浩廷 Jensen Li Gyu-Boong Jo Department of Physics The Hong Kong University of Science and TechnologyKowloon 999077China

Accurately measuring magnetic fields is essential for magnetic-field sensitive experiments in areas like atomic,molecular,and optical physics,condensed matter experiments,and other ***,since many experiments are often conducted in an isolated environment that is inaccessible to experimentalists,it can be challenging to accurately determine the magnetic field at the target ***,we propose an efficient method for detecting magnetic fields with the assistance of an artificial neural network(NN).Instead of measuring the magnetic field directly at the desired location,we detect fields at several surrounding positions,and a trained NN can accurately predict the magnetic field at the target *** training,we achieve a below 0.3%relative prediction error of magnetic field magnitude at the center of the vacuum chamber,and successfully apply this method to our erbium quantum gas apparatus for accurate calibration of magnetic field and long-term monitoring of environmental stray magnetic *** demonstrated approach significantly simplifies the process of determining magnetic fields in isolated environments and can be applied to various research fields across a wide range of magnetic field magnitudes.

关键词： ultracold gases trapped gases measurement methods and instrumentation