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Quantization and Event-Triggered Policy Design for Encrypted Networked Control

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 946-955页

作者： Yongxia Shi Ehsan Nekouei the department of Electrical Engineering City University of Hong KongHong KongChina

This paper proposes a novel event-driven encrypted control framework for linear networked control systems(NCSs),which relies on two modified uniform quantization policies,the Paillier cryptosystem,and an event-triggered *** to the fact that only integers can work in the Pailler cryptosystem,both the real-valued control gain and system state need to be first quantized before *** is dramatically different from the existing quantized control methods,where only the quantization of a single value,e.g.,the control input or the system state,is *** handle this issue,static and dynamic quantization policies are presented,which achieve the desired integer conversions and guarantee asymptotic convergence of the quantized system state to the ***,the quantized system state is encrypted and sent to the controller when the triggering condition,specified by a state-based event-triggered strategy,is *** doing so,not only the security and confidentiality of data transmitted over the communication network are protected,but also the ciphertext expansion phenomenon can be ***,by tactfully designing the quantization sensitivities and triggering error,the proposed event-driven encrypted control framework ensures the asymptotic stability of the overall closedloop ***,a simulation example of the secure motion control for an inverted pendulum cart system is presented to evaluate the effectiveness of the theoretical results.

关键词： Cyber-security encrypted control event-triggered control(ETC) networked control systems(NCSs) semi-homomorphic encryption

Directly predicting N_(2) electroreduction reaction free energy using interpretable machine learning with non-DFT calculated features

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Journal of Energy Chemistry 2024年第10期97卷 139-148,I0004页

作者： Yaqin Zhang Yuhang Wang Ninggui Ma Jun Fan department of Materials Science and Engineering City University of Hong KongHong Kong 999077China Center for Advanced Nuclear Safety and Sustainable Development City University of Hong KongHong Kong 9077China department of Mechanical Engineering City University of Hong KongHong Kong 999077China

Electrocatalytic nitrogen reduction to ammonia has garnered significant attention with the blooming of single-atom catalysts(SACs),showcasing their potential for sustainable and energy-efficient ammonia ***,cost-effectively designing and screening efficient electrocatalysts remains a *** this study,we have successfully established interpretable machine learning(ML)models to evaluate the catalytic activity of SACs by directly and accurately predicting reaction Gibbs free *** models were trained using non-density functional theory(DFT)calculated features from a dataset comprising 90 graphene-supported *** results underscore the superior prediction accuracy of the gradient boosting regression(GBR)model for bothΔg(N_(2)→NNH)andΔG(NH_(2)→NH_(3)),boasting coefficient of determination(R^(2))score of 0.972 and 0.984,along with root mean square error(RMSE)of 0.051 and 0.085 eV,***,feature importance analysis elucidates that the high accuracy of GBR model stems from its adept capture of characteristics pertinent to the active center and coordination environment,unveilling the significance of elementary descriptors,with the colvalent radius playing a dominant ***,Shapley additive explanations(SHAP)analysis provides global and local interpretation of the working mechanism of the GBR *** analysis identifies that a pyrrole-type coordination(flag=0),d-orbitals with a moderate occupation(N_(d)=5),and a moderate difference in covalent radius(r_(TM-ave)near 140 pm)are conducive to achieving high ***,we extend the prediction of activity to more catalysts without additional DFT calculations,validating the reliability of our feature engineering,model training,and design *** findings not only highlight new opportunity for accelerating catalyst design using non-DFT calculated features,but also shed light on the working mechanism of"black box"ML ***,the model provides valuable g

关键词： Nitrogen reduction Single-atom catalyst Interpretable machine learning Graphene Non-DFT features

Entangled photons enabled ultrafast stimulated Raman spectroscopy for molecular dynamics

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Light(Science & Applications) 2024年第8期13卷 1615-1622页

作者： Jiahao Joel Fan Zhe-Yu Ou Zhedong Zhang department of Physics City University of Hong KongKowloonHong Kong SARChina city university of hong kong Shenzhen Research InstituteShenzhenGuangdongChina

Quantum entanglement has emerged as a great resource for studying the interactions between molecules and *** propose a new scheme of stimulated Raman scattering with entangled photons.A quantum ultrafast Raman spectroscopy is developed for condensed-phase molecules,to monitor the exciton populations and *** results are obtained,showing an entanglement-enabled time-frequency scale not attainable by classical *** Raman signal presents an unprecedented selectivity of molecular correlation functions,as a result of the hong-Ou-Mandel *** work suggests a new paradigm of using an unconventional interferometer as part of spectroscopy,with the potential to unveil advanced information about complex materials.

关键词： materials spectroscopy selectivity

Metal/covalent organic frameworks for aqueous rechargeable zinc-ion batteries

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Science China Chemistry 2024年第1期67卷 247-259页

作者： Hu hong Xun Guo Jiaxiong Zhu Zhuoxi Wu Qing Li Chunyi Zhi department of Materials Science and Engineering City University of Hong KongHong Kong 999077China

Lithium-ion batteries(LIBs)have become one of the most successful energy storage systems due to their high operating voltage,high energy density,and long cycle ***,with the widespread use of LIBs in recent decades,lithium resources are at risk of being ***,it is necessary to find a substitute for LIBs to meet the needs of future large-scale energy storage *** of their competitiveness,low cost,and high safety,aqueous rechargeable zinc-ion batteries(ARZIBs)are regarded as promising components in the post-lithium-ion-battery *** the tunable composition,ordered porous channels,and controllable structure of metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),these frameworks are viewed as potential materials for developing high-performance *** this review,we focus on the recent developments in the applications of MOF-/COF-based materials in ARZIBs,including in electrode materials,anode modifications,separators,and solid *** then focus on the critical factors and optimization techniques of MOF-/COF-based materials that affect the performance of ***,we conclude with some projections for the expansion of ARZIBs containing MOF-/COF-based materials.

关键词： metal/covalent organic frameworks aqueous zinc-ion batteries electrode materials anode modifications separators electrolytes

Immersive visualization of 3D subsurface ground model developed from sparse boreholes using virtual reality(VR)

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Underground Space 2024年第4期17卷 188-206页

作者： Borui Lyu Yu Wang department of Architecture and Civil Engineering City University of Hong KongKowloon 999077Hong KongChina

Analytics and visualization of multi-dimensional and complex geo-data,such as three-dimensional(3D)subsurface ground models,is critical for development of underground space and design and construction of underground structures(e.g.,tunnels,dams,and slopes)in engineering *** complicated 3D subsurface ground models now can be developed from site investigation data(e.g.,boreholes)which is often sparse in practice,it remains a great challenge to visualize a 3D subsurface ground model with sophisticated stratigraphic variations by conventional two-dimensional(2D)geological *** reality(VR)technology,which has an attractive capability of constructing a virtual environment that links to the physical world,has been rapidly developed and applied to visualization in various disciplines *** on the rapid development of VR,this study proposes a framework for immersive visualization of 3D subsurface ground models in geo-applications using VR *** 3D subsurface model is first developed from limited borehole data in a data-driven ***,a VR system is developed using related software and hardware devices currently available in the markets for immersive visualization and interaction with the developed 3D subsurface ground *** results demonstrate that VR visualization of the 3D subsurface ground model in an immersive environment has great potential in revolutionizing the geo-practices from 2D cross-sections to a 3D immersive virtual environment in digital era,particularly for the emerging digital twins.

关键词： Immersive visualization 3D subsurface model Virtual reality Virtual environment Interaction

Generic load regulation strategy for enhancing energy efficiency of chiller plants

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Building Simulation 2024年第8期17卷 1273-1287页

作者： Hang Wan Yuyang Gong Shengwei Wang Yongjun Sun Tao Xu Gongsheng Huang department of Architecture and Civil Engineering City University of Hong KongHong KongChina department of Building Environment and Energy Engineering Hong Kong Polytechnic UniversityHong KongChina School of Civil Engineering Guangzhou UniversityGuangzhouChina Shenzhen Research Institute of city university of hong kong ShenzhenChina

In many chiller plants,high coefficient of performance(COP)is only achieved at a few favorable part load ratios(PLRs),while the COP is low at many other non-favorable *** address this issue,this study proposes a generic load regulation strategy that aims to maintain chiller plants operating at high COP,particularly under non-favorable *** is achieved by incorporating thermal energy storage(TES)units and timely optimizing the charging and discharging power of the integrated TES *** optimal charging and discharging power is determined by solving a dynamic optimization problem,taking into account the performance constraints of the TES units and the chiller *** provide an overview of the energy-saving potential of the proposed strategy,a comprehensive analysis was conducted,considering factors such as building load profiles,COP/PLR curves of chillers,and attributes of the TES *** analysis revealed that the proposed load regulation strategy has the potential to achieve energy savings ranging from 5.7%to 10.8%for chiller plants with poor COPs under unfavorable PLRs,particularly in buildings with significant load variations.

关键词： load regulation thermal energy storage chiller plants building energy efficiency

Wettability Gradient-Induced Diode:MXene-Engineered Membrane for Passive-Evaporative Cooling

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Nano-Micro Letters 2024年第8期16卷 382-397页

作者： Leqi Lei Shuo Meng Yifan Si Shuo Shi Hanbai Wu Jieqiong Yang Jinlian Hu department of Biomedical Engineering City University of Hong KongHong Kong S.A.R 999077China

Thermoregulatory textiles,leveraging high-emissivity structural materials,have arisen as a promising candidate for personal cooling management;however,their advancement has been hindered by the underperformed water moisture transportation capacity,which impacts on their thermophysiological ***,we designed a wettability-gradient-induced-diode(WGID)membrane achieving by MXene-engineered electrospun technology,which could facilitate heat dissipation and moisture-wicking *** a result,the obtained WGID membrane could obtain a cooling temperature of 1.5℃ in the“dry”state,and 7.1℃ in the“wet”state,which was ascribed to its high emissivity of 96.40%in the MIR range,superior thermal conductivity of 0.3349 W m^(-1) K^(-1)(based on radiation-and conduction-controlled mechanisms),and unidirectional moisture transportation *** proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation,thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment.

关键词： Passive-evaporative cooling MXene Electrospun membrane Wettability gradient Diode

Advancing large-scale thin-film PPLN nonlinear photonics with segmented tunable micro-heaters

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Photonics Research 2024年第8期12卷 1703-1708页

作者： XIAOTING LI HAOCHUAN LI ZHENZHENG WANG ZHAOXI CHEN FEI MA KE ZHANG WENZHAO SUN CHENG WANG department of Electrical Engineering City University of Hong KongHong KongChina School of Physics Sun Yat-sen UniversityGuangzhou 510275China city university of hong kong(Dongguan) Dongguan 523808China Center of Information and Communication Technology City University of Hong Kong Shenzhen Research InstituteShenzhen 518057China State Key Laboratory of Terahertz and Millimeter Waves City University of Hong KongHong KongChina

Thin-film periodically poled lithium niobate(TF-PPLN)devices have recently gained prominence for efficient wavelength conversion processes in both classical and quantum ***,the patterning and poling of TF-PPLN devices today are mostly performed at chip scales,presenting a significant bottleneck for future largescale nonlinear photonic systems that require the integration of multiple nonlinear components with consistent performance and low ***,we take a pivotal step towards this goal by developing a wafer-scale TF-PPLN nonlinear photonic platform,leveraging ultraviolet stepper lithography and an automated poling *** address the inhomogeneous broadening of the quasi-phase matching(QPM)spectrum induced by film thickness variations across the wafer,we propose and demonstrate segmented thermal optic tuning modules that can precisely adjust and align the QPM peak wavelengths in each *** the segmented micro-heaters,we show the successful realignment of inhomogeneously broadened multi-peak QPM spectra with up to 57%enhancement of conversion *** achieve a high normalized conversion efficiency of 3802%W-1cm-2in a 6 mm long PPLN waveguide,recovering 84%of the theoretically predicted efficiency in this *** advanced fabrication techniques and segmented tuning architectures presented herein pave the way for wafer-scale integration of complex functional nonlinear photonic circuits with applications in quantum information processing,precision sensing and metrology,and low-noise-figure optical signal amplification.

关键词： tuning tunable waveguide

Hierarchical crystalline-amorphous nanocomposites with high strength and large deformability enabled by elemental diffusion

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Journal of Materials Science & Technology 2024年第4期171卷 150-161页

作者： Liqiang Wang Heyi Wang Xin Zhou Huangliu Fu James Utama Surjadi Shuo Qu Xu Song Rong Fan Yang Lu department of Mechanical Engineering City University of Hong KongHong KongChina Nano-Manufacturing Laboratory(NML) Shenzhen Research Institute of City University of Hong KongShenzhen 518057China Chengdu Research Institute City University of Hong KongChengdu 610200China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina department of Mechanical Engineering The University of Hong KongHong KongChina

Amorphous/nanocrystalline dual-phase structures have recently emerged as an effective way for over-coming the strength-ductility trade-offand breaking the limitation of the reverse Hall-Petch ***,we proposed a new strategy to develop a hierarchical and interconnected amorphous-crystalline nanocomposite arising from the nanoscale elemental interdiffusion and oxygen adsorption behavior dur-ing thermal treatment *** nanocomposite consisted of a three-dimensional(3D)hierarchical network structure where the crystalline phase(Cr-Co-Ni-Al)was embedded into the Al-O-based amor-phous phase network with critical feature sizes encompassing three orders of magnitude(from microm-eter to nanometer scale).It can achieve ultrahigh compression yield strength of-3.6 GPa with large homogeneous deformation of over 50%*** massive interstitial atoms induced lattice distortion and hierarchical amorphous phase boundary contributed to the strength *** situ Uniaxial compression inside a transmission electron microscope(TEM)revealed that the exceptional deformability of the nanocomposites resulted from the homogenous plastic flow of nano-sized amorphous phase and the plastic co-deformation behavior restricted by the nano-architected dual-phase *** proposed dual-phase synthesis approach can outperform conventional nanolaminates design strategies in terms of the mechanical properties achievable while providing a pathway to easily tune the microstructure of these nanolaminates.

关键词： Nanolaminates Dual-phase nanocomposites In situ transmission electron microscopy Multi-component alloy