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Ultra-highly sensitive dual gases detection based on photoacoustic spectroscopy by exploiting a long-wave,high-power,wide-tunable,singlelongitudinal-mode solid-state laser

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Light(Science & Applications) 2024年第5期13卷 941-956页

作者： Shunda Qiao Ying He Haiyue Sun Pietro Patimisco Angelo Sampaolo Vincenzo Spagnolo Yufei Ma national Key Laboratory of Laser Spatial Information Harbin Institute of TechnologyHarbinChina PolySense Lab Dipartimento Interateneo di FisicaUniversity and Politecnico of BariVia AmendolaBariItaly

Photoacoustic spectroscopy(PAS)as a highly sensitive and selective trace gas detection technique has extremely broad application in many ***,the laser sources currently used in PAS limit the sensing *** to diode laser and quantum cascade laser,the solid-state laser has the merits of high optical power,excellent beam quality,and wide tuning *** we present a long-wave,high-power,wide-tunable,singlelongitudinal-mode solid-state laser used as light source in a PAS sensor for trace gas *** self-built solid-state laser had an emission wavelength of~2μm with Tm:YAP crystal as the gain material,with an excellent wavelength and optical power stability as well as a high beam *** wide wavelength tuning range of 9.44 nm covers the absorption spectra of water and ammonia,with a maximum optical power of~130 mW,allowing dual gas detection with a single laser *** solid-state laser was used as light source in three different photoacoustic detection techniques:standard PAS with microphone,and external-and intra-cavity quartz-enhanced photoacoustic spectroscopy(QEPAS),proving that solid-state laser is an attractive excitation source in photoacoustic spectroscopy.

关键词： power tunable tuning

Incoherent non-Hermitian skin effect in photonic quantum walks

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Light(Science & Applications) 2024年第5期13卷 885-893页

作者： Stefano Longhi Dipartimento di Fisica Politecnico di MilanoPiazza L.da Vinci 32I-20133 MilanoItaly IFISC(UIB-CSIC) Instituto de Fisica Interdisciplinar y Sistemas ComplejosE-07122 Palma de MallorcaSpain

The non-Hermitian skin effect describes the concentration of an extensive number of eigenstates near the boundaries of certain dissipative *** phenomenon has raised a huge interest in different areas of physics,including photonics,deeply expanding our understanding of non-Hermitian systems and opening up new avenues in both fundamental and applied aspects of topological *** skin effect has been associated to a nontrivial pointgap spectral topology and has been experimentally demonstrated in a variety of synthetic matter systems,including photonic *** most of physical models exhibiting the non-Hermitian skin effect full or partial wave coherence is generally *** we push the concept of skin effect into the fully incoherent regime and show that rather generally(but not universally)the non-Hermitian skin effect persists under dephasing *** results are illustrated by considering incoherent light dynamics in non-Hermitian photonic quantum walks.

关键词： dynamics. quantum effect

Modelling dynamic pantograph loads with combined numerical analysis

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Railway Engineering Science 2024年第1期32卷 81-94页

作者： F.F.Jackson R.Mishra J.M.Rebelo J.Santos P.Antunes J.Pombo H.Magalhaes L.Wills M.Askill School of Computing and Engineering University of HuddersfieldHuddersfieldUK School of Computing and Engineering Institute of Railway ResearchUniversity of HuddersfieldHuddersfieldUK IDMEC Instituto Superior TecnicoUniversidade de LisboaLisbonPortugal ISEL Instituto Politecnico de LisboaLisbonPortugal Hitachi Rail Newton AycliffeUK Wabtec/Brecknell Willis ChardUK

Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric *** heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile,and thus aerodynamic load changes significantly with operational *** research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations,such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact ***,computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting,such as that of the recessed cavity on a Class 800 *** an aerodynamic perspective,this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing,although the difference between the two is found to reduce with increasing pantograph *** the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph *** results obtained show how considering aerodynamic forces enhance the realism of the models,leading to behaviour of the pantograph-catenary contact forces closely matching that seen in experimental tests.

关键词： Pantograph-catenary interaction Pantograph aerodynamics Computational fluid dynamics Pantograph loads Current collection performance

Hydrogeochemical and isotopic assessment of the origin of NO_(3)^(−)and N-NH_(3)contents in the aquifer located in a closed lacustrine volcano-sedimentary basin in the metropolitan area of Mexico City

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Acta Geochimica 2024年第4期43卷 719-736页

作者： Jose Ivan Morales-Arredondo Maria Aurora Armienta Hernandez Joel Edmundo Ortega-Gutierrez Elisa Cuellar Ramirez Natural Resources Department Institute of GeophysicsNational Autonomous University of MexicoCiudad Universitaria No.3000Col.Copilco UniversidadCoyoacán Delegation04360 MexicoCDMXMexico instituto politecnico Nacional ***án 55La Laguna Ticoman07340 MexicoCDMXMexico Benemérita Universidad Autónoma de Puebla Ciudad Universitaria Col.San ManuelPueblaPueMexico

To explain the presence and spatial distribution of NO_(3)^(−)and N-NH_(3)in the Aquifer of the Metropolitan Area of Mexico City(AMAMC),a hydrogeochemical and isotopic analysis using^(13)C DIC(as well as the stable isotopes^(18)O and^(2)H)in groundwater was *** aquifer is located in an old closed lacustrine volcano-sedimentary basin;some wells hosted in the semi-confined zone contain high N-NH_(3)concentrations,while others present NO_(3)^(−)contents in the recharge zones(hosted in an oxidizing environment).In this study,a change in the isotopic signature(primarily in^(18)O and^(2)H)was observed from the recharge zones to the basin center in some of the wells with high NO_(3)^(−)concentrations,this behavior can be attributed to evaporation during the incorporation of recently infiltrated *** addition,the results for^(13)C(along with ^(2) H)in wells with the highest N-NH_(3)concentrations exhibited an atypically broad range of *** indicated the occurrence of hydrogeochemical and/or biochemical processes in the aquifer(in an oxidizing or reducing environment),such as organic degradation,bacterial decomposition(primarily in the ancient Lake Texcoco and which acts as a natural sink for carbon,nitrogen,sulfur,and phosphorus),besides rock weathering and dissolution,which may be responsible for a very marked isotopic modification of the^(13)C(and,to a lesser extent,2 H).Methanotrophic bacterial activity and methanogenic activity may be related to N-NH_(3)removal processes by oxidation and residual water incorporation respectively,whereas the increase in the NO_(3)^(−)content in some wells is due to the recent contribution of poor-quality water due to contamination.

关键词： 18 O and^(13)C isotopes Iron Hydrogeochemical processes Nitrate Nitrogen species

An innovative heterogeneous transfer learning framework to enhance the scalability of deep reinforcement learning controllers in buildings with integrated energy systems

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Building Simulation 2024年第5期17卷 739-770页

作者： Davide Coraci Silvio Brandi Tianzhen Hong Alfonso Capozzoli politecnico di Torino Department of EnergyTEBE research groupBAEDA Lab.Corso Duca degli Abruzzi 24Torino10129Italy Building Technology and Urban Systems Division Lawrence Berkeley National LaboratoryOne Cyclotron RoadBerkeleyCA 94720USA

Deep Reinforcement Learning(DRL)-based control shows enhanced performance in the management of integrated energy systems when compared with Rule-Based Controllers(RBCs),but it still lacks scalability and generalisation due to the necessity of using tailored models for the training *** Learning(TL)is a potential solution to address this ***,existing TL applications in building control have been mostly tested among buildings with similar features,not addressing the need to scale up advanced control in real-world scenarios with diverse energy *** paper assesses the performance of an online heterogeneous TL strategy,comparing it with RBC and offline and online DRL controllers in a simulation setup using EnergyPlus and *** study tests the transfer in both transductive and inductive settings of a DRL policy designed to manage a chiller coupled with a Thermal Energy Storage(TES).The control policy is pre-trained on a source building and transferred to various target buildings characterised by an integrated energy system including photovoltaic and battery energy storage systems,different building envelope features,occupancy schedule and boundary conditions(e.g.,weather and price signal).The TL approach incorporates model slicing,imitation learning and fine-tuning to handle diverse state spaces and reward functions between source and target *** show that the proposed methodology leads to a reduction of 10% in electricity cost and between 10% and 40% in the mean value of the daily average temperature violation rate compared to RBC and online DRL ***,online TL maximises self-sufficiency and self-consumption by 9% and 11% with respect to ***,online TL achieves worse performance compared to offline DRL in either transductive or inductive ***,offline Deep Reinforcement Learning(DRL)agents should be trained at least for 15 episodes to reach the same level of performance as the online

关键词： transfer learning reinforcement learning building control building energy management

Adaptive multi-channel Bayesian graph attention network for IoT transaction security

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Digital Communications and Networks 2024年第3期10卷 631-644页

作者： Zhaowei Liu Dong Yang Shenqiang Wang Hang Su School of Computer and Control Engineering Yantai UniversityYantai264005China Department of Electronics Information and BioengineeringPolitecnico di MilanoMilan20133Italy

With the rapid advancement of 5G technology,the Internet of Things(IoT)has entered a new phase of appli-cations and is rapidly becoming a significant force in promoting economic *** to the vast amounts of data created by numerous 5G IoT devices,the Ethereum platform has become a tool for the storage and sharing of IoT device data,thanks to its open and tamper-resistant ***,Ethereum account security is necessary for the Internet of Things to grow quickly and improve people's *** modeling Ethereum trans-action records as a transaction network,the account types are well identified by the Ethereum account classifi-cation system established based on Graph Neural Networks(GNNs).This work first investigates the Ethereum transaction ***,experimental metrics reveal that the Ethereum transaction network is neither optimal nor even satisfactory in terms of accurately representing transactions per *** flaw may significantly impede the classification capability of GNNs,which is mostly governed by their *** work proposes an Adaptive Multi-channel Bayesian Graph Attention Network(AMBGAT)for Ethereum account clas-sification to address this *** uses attention to enhance node features,estimate graph topology that conforms to the ground truth,and efficiently extract node features pertinent to downstream *** extensive experiment with actual Ethereum transaction data demonstrates that AMBGAT obtains competitive performance in the classification of Ethereum accounts while accurately estimating the graph topology.

关键词： Internet of things Graph representation learning Node classification Security mechanism

A chaotic hierarchical encryption/watermark embedding scheme for multi-medical images based on row-column confusion and closed-loop bi-directional diffusion

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Chinese Physics B 2024年第2期33卷 228-237页

作者：张哲祎牟俊 Santo Banerjee 曹颖鸿 School of Information Science and Engineering Dalian Polytechnic UniversityDalian 116034China Department of Mathematical Sciences Politecnico di TorinoTorino 10129Italy

Security during remote transmission has been an important concern for researchers in recent *** this paper,a hierarchical encryption multi-image encryption scheme for people with different security levels is designed,and a multiimage encryption(MIE)algorithm with row and column confusion and closed-loop bi-directional diffusion is adopted in the *** ensuring secure communication of medical image information,people with different security levels have different levels of decryption keys,and differentiated visual effects can be obtained by using the strong sensitivity of chaotic *** highest security level can obtain decrypted images without watermarks,and at the same time,patient information and copyright attribution can be verified by obtaining watermark *** experimental results show that the scheme is sufficiently secure as an MIE scheme with visualized differences and the encryption and decryption efficiency is significantly improved compared to other works.

关键词： chaotic hierarchical encryption multi-medical image encryption differentiated visual effects row-column confusion closed-loop bi-directional diffusion transform domain watermark embedding

Optimization of a photovoltaic-battery system using deep reinforcement learning and load forecasting

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Energy and AI 2024年第2期16卷 168-183页

作者： António Corte Real G.Pontes Luz J.M.C.Sousa M.C.Brito S.M.Vieira IDMEC Instituto Superior TécnicoUniversidade de LisboaLisboa1049-001Portugal instituto Dom Luiz Faculdade de CiênciasUniversidade de LisboaCampo Grande1749-016LisboaPortugal

Home Energy Management Systems(HEMS)are increasingly relevant for demand-side management at the residential level by collecting data(energy,weather,electricity prices)and controlling home appliances or storage *** control can be performed with classical models that find optimal solutions,with high real-time computational cost,or data-driven approaches,like Reinforcement Learning,that find good and flexible solutions,but depend on the availability of load and generation data and demand high computational resources for *** this work,a novel HEMS is proposed for the optimization of an electric battery operation in a real,online and data-driven environment that integrates state-of-the-art load forecasting combining CNN and LSTM neural networks to increase the robustness of *** Reinforcement Learning agents are trained with different algorithms(Double DQN,Dueling DQN,Rainbow and Proximal Policy Optimization)in order to minimize the cost of electricity purchase and to maximize photovoltaic self-consumption for a PV-Battery residential *** show that the best Reinforcement Learning agent achieves a 35%reduction in total cost when compared with an optimization-based agent.

关键词： Energy management system Deep reinforcement learning Demand-side management Load forecasting Deep learning Energy storage systems

Actuating droplets with electrowetting: Force and dynamics

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Droplet 2024年第2期3卷 113-124页

作者： Robert Hennig Vito Cacucciolo Herbert Shea Soft Transducers Laboratory(LMTS) Ecole Polytechnique Fédérale de Lausanne(EPFL)NeuchatelSwitzerland politecnico di Bari BariItaly

Electrowetting on dielectric(EWOD)allows rapid movement of liquid droplets on a smooth surface,with applications ranging from lab-on-chip devices to *** in-plane force on a droplet is a key indicator of EWOD *** force has been extensively modeled but few direct experimental measurements are *** study the EWOD force on a droplet using two setups that allow,for the first time,the simultaneous measurement of force and contact angle,while imaging the droplet shape at 6000 frames/*** several liquids and surfaces,we observe that the force saturates at a voltage of approximately 150 *** of voltages of up 2 kV,that is,10 times higher than is typical,does not significantly increase forces beyond the saturation ***,we observe that the transient dynamics,localized at the front contact line,do not show saturation with *** the higher voltages,the initial front contact line speed continues to increase,the front contact angle temporarily becomes near zero,creating a thin liquid film,and capillary waves form at the liquid–air *** the localized EWOD forces at the contact line exceed the capillary forces,projectile droplets *** surface tension allows for higher droplet forces,which we demonstrate with mercury.

关键词： capillary forces dynamics