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The quasi-Gramian solution of a non-commutative extension of the higher-order nonlinear Schr?dinger equation

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Communications in Theoretical Physics 2024年第3期76卷 51-61页

作者： h W A Riaz J lin Department of Physics Zhejiang Normal UniversityJinhua 321004China

The nonlinear Schr?dinger(NLS)equation,which incorporates higher-order dispersive terms,is widely employed in the theoretical analysis of various physical *** this study,we explore the non-commutative extension of the higher-order NLS *** treat real or complex-valued functions,such as g_(1)=g_(1)(x,t)and g_(2)=g_(2)(x,t)as non-commutative,and employ the Lax pair associated with the evolution equation,as in the commutation *** derive the quasi-Gramian solution of the system by employing a binary Darboux *** soliton solutions are presented explicitly within the framework of *** visually understand the dynamics and solutions in the given example,we also provide simulations illustrating the associated ***,the solution can be used to study the stability of plane waves and to understand the generation of periodic patterns within the context of modulational instability.

关键词： integrable systems Darboux transformation solitons

Discrete Boltzmann model with split collision for nonequilibrium reactive flows

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Communications in Theoretical Physics 2024年第8期76卷 164-186页

作者： Chuandong lin Kai h Luo huilin Lai Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Department of Mechanical Engineering National University of Singapore10 Kent Ridge Crescent119260Singapore Department of Mechanical Engineering University College LondonTorrington PlaceLondon WC1E 7JEUnited Kingdom School of Mathematics and Statistics Key Laboratory of Analytical Mathematics and Applications(Ministry of Education)Fujian Key Laboratory of Analytical Mathematics and Applications(FJKLAMA)Center for Applied Mathematics of Fujian Province(FJNU)Fujian Normal University350117 FuzhouChina

A multi-relaxation-time discrete Boltzmann model(DBM) with split collision is proposed for both subsonic and supersonic compressible reacting flows, where chemical reactions take place among various components. The physical model is based on a unified set of discrete Boltzmann equations that describes the evolution of each chemical species with adjustable acceleration, specific heat ratio, and Prandtl number. On the right-hand side of discrete Boltzmann equations, the collision,force, and reaction terms denote the change rates of distribution functions due to self-and crosscollisions, external forces, and chemical reactions, respectively. The source terms can be calculated in three ways, among which the matrix inversion method possesses the highest physical accuracy and computational efficiency. Through Chapman-Enskog analysis, it is proved that the DBM is consistent with the reactive Navier-Stokes equations, Fick's law and the Stefan-Maxwell diffusion equation in the hydrodynamic limit. Compared with the one-step-relaxation model, the split collision model offers a detailed and precise description of hydrodynamic, thermodynamic, and chemical nonequilibrium effects. Finally, the model is validated by six benchmarks, including multicomponent diffusion, mixture in the force field, Kelvin-helmholtz instability, flame at constant pressure, opposing chemical reaction, and steady detonation.

关键词： discrete Boltzmann method reactive flow detonation nonequilibrium effect

Integralinput-to-statestability ystemswithsmalldelays Integral input-to-state stability of systems with small delays

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Control Theory and Technology 2024年第3期22卷 455-467页

作者： R.h.harsha Nawarathna Yuandan lin Yuan Wang Department of Mathematical Sciences Florida Atlantic UniversityBoca RatonFL 33431USA

We consider how small delays affect the integral-input-to-state stability(iss)property for a *** result is similar to the input-to-state stability(Iss)result obtained in[1]:the iss property will be preserved in a practical and semi-global manner if the delay interval is small ***,since the iss quantifies the robust stability in terms of a generalized Li norm of the inputs instead of a generalized Loo norm of the inputs for the Iss case,the techniques and proofs for the Iss case do not apply to the iss case *** the proofs in[1]are based on the Lyapunov-Razumikhin approach,our proofs are based on the iss-Lyapunov functions for the zero-delay *** addition to the interest by its own in showing how the iss property is affected by small delays,the result also serves to the study of the iss property for singularly perturbed systems.

关键词： Integral-input-to-state stability Nonlinear systems Small delays Lyapunov method

Estimating Critical Clearing Time of Grid Faults Using DA of State-Reduction Model of Power Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 807-820页

作者： Yang Liu Zhongyang Chen huanjin Yao lin Yi Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China China Southern Power Grid Research Institute Guangzhou 510663China

This paper proposes a critical clearing time (CCT) estimation method by the domain of attraction (DA) of a state-reduction model of power systems using sum of squares (SOS) programming. By exploiting the property of the Jacobian matrix and the structure of the boundary of the DA, it is found the DA of the state-reduction model and that of the full model of a power system are topological isomorphism. There are one-to-one correspondence relationships between the number of equilibrium points, the type of equilibrium points, and solutions of the two system models. Based on these findings, an expanding interior algorithm is proposed with SOS programming to estimate the DA of the state-reduction model. State trajectories of the full model can be transformed to those of the state-reduction model by orthogonal or equiradius projection. In this way, CCT of a grid fault is estimated with the DA of the state-reduction model. The calculational burden of SOS programming in the DA estimation using the state-reduction model is rather small compared with using the full model. Simulation results show the proposed expanding interior algorithm is able to provide a tight estimation of DA of power systems with higher accuracy and lower time costs.

关键词： Critical clearing time domain of attraction expanding interior algorithm state-reduction model SOS programming

Expanding Annular Domain Algorithm to Estimate Domains of Attraction for Power System Stability Analysis

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 1925-1934页

作者： Yuqing lin Tianhao Wen Yang Liu Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

This paper presents an Expanding Annular Domain(EAD)algorithm combined with Sum of Squares(SOS)programming to estimate and maximize the domain of attraction(DA)of power *** proposed algorithm can systematically construct polynomial Lyapunov functions for power systems with transfer conductance and reliably determine a less conservative approximated DA,which are quite difficult to achieve with traditional *** linear SOS programming,we begin from an initial estimated DA,then enlarge it by iteratively determining a series of so-called annular domains of attraction,each of which is characterized by level sets of two successively obtained Lyapunov ***,the EAD algorithm is theoretically analyzed in detail and its validity and convergence are shown under certain *** the end,our method is tested on two classical power system cases and is demonstrated to be superior to existing methods in terms of computational speed and conservativeness of results.

关键词： Domain of attraction Lyapunov functions power system transient stability sum of squares programming

Decorating crystalline YFe_(2-x)Al_(x) on the Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy as “hydrogen pump” to realize fast de/hydrogenation

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Journal of Materials Science & Technology 2024年第6期173卷 72-79页

作者： L.J.huang h.Wang L.Z.Ouyang M.Zhu h.J.lin School of Materials Science and Engineering Key Laboratory of Advanced Energy Storage Materials of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510641China Institute of Advanced Wear&Corrosion Resistance and Functional Materials Jinan UniversityGuangzhou 510632China

Mg-based amorphous alloys are one of the potential hydrogen storage materials but suffer from sluggish dehydrogenation/hydrogenation(de/hydrogenation)*** this work,as a new strategy,a hydrogen pump is built on the surface of amorphous alloys to solve this *** milling crystalline YFe_(2-x)Al_(x) hydrogen storage alloy with Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy,fine crystalline particles were seeded on amorphous alloy powder to form a“strawberry”*** to the TEM observation,a metallurgical bonding boundary formed between the Mg-based amorphous matrix and the Y-Fe-Al crystalline *** microstructure and de/hydrogenation kinetics investigation,the“hydrogen pump”effect of the seeded crystalline alloy was confirmed,which makes it much easier for the hydrogen to dissociate on and diffuse through the surface of the Mg-based amorphous *** such effect,the h absorption rate of Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy became almost eight times faster and it absorbs ~2.8 wt.% in 1 h at 130℃ under 4.5 MPa-h_(2).Further,fast hydrogenation can even achieve at 70℃ and the low-temperature dehydrogenation kinetics of the amorphous hydride can be also greatly *** present work proves that surface modification is of great importance for obtaining Mg-based amorphous alloy with ideal hydrogen storage performance.

关键词： hydrogen storage Mg-based amorphous alloy hydrogen pump Composite structure

Selective photosynthesis of imines from biomass-derived aldehydes over Ni/TiO_(2)

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Rare Metals 2024年第3期43卷 1116-1124页

作者： Wu-lin Li Qing-Qing Zhang lin Dong Wen-Jun Zhang Li-Li lin Zu-Peng Chen Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing210037China Institute of Industrial Catalysis State Key Laboratory of Green Chemistry Synthesis TechnologyCollege of Chemical EngineeringZhejiang University of TechnologyHangzhou310014China

Photocatalytic reductive amination of biomass-derived aldehydes is a desirable way to selectively upgrade biomass into value-added nitrogen-containing chemicals under mild ***,it is challenging to produce imines in high selectivity because of the undesirable side reactions caused by the activity of functional ***,we demonstrate the highly reactive and selective production of imines from biomass derived aldehydes via the photocatalytic reductive amination,using a defective TiO_(2)supported nickel *** employment of methanol as the hydrogen donor and ammonia solution as the nitrogen source avoids the use of high-pressure h_(2)and expensive amines,rendering the current catalytic process safe,economical,and environmentally *** depth investigations attribute the improved separation and transfer of photogenerated charge carriers to the presence of oxygen vacancies and decorated Ni nanoparticles,thereby accelerating the production of imines from benzaldehyde amination(conversion,95.8%;seleetivity,95.2%).Furthermore,the developed system could be easily translated to the photocatalytic conversions of various biomass derived aldehydes,which provided an example of a cost-effective and sustainable approach for the valorization of biomass derived feedstocks.

关键词： Photocatalysis Biomass derivatives Imines Reduction amination heterogeneous catalyst

Mechanism study of Cu(Ⅱ) adsorption from acidic wastewater by ultrasonic-modified municipal solid waste incineration fly ash

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Chinese Journal of Chemical Engineering 2024年第3期67卷 157-165页

作者： Shunda lin Yang Lu lin Zheng ling Long Xuguang Jiang Jianhua Yan State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China Zhejiang University Qingshanhu Energy Research Center Hangzhou 310027China hangzhou Xiaoshan Jinjiang Green Energy Co. Ltd.XiaoshanHangzhou 310000China

high concentrations of copper ions(Cu(Ⅱ)) in water will pose health risks to humans and the ecological environment. Therefore, this study aims to utilize ultrasonic-cured modified municipal solid waste incineration(MSWI) fly ash for Cu(Ⅱ) adsorption to achieve the purpose of “treating waste by waste.” The effects of p h, adsorption time, initial concentration, and temperature on the modified MSWI fly ash’s adsorption efficiency were systematically studied in this article. The adsorption performance of the modified MSWI fly ash can be enhanced by the ultrasonic modification. At ph = 2, 3 and 4, the adsorption capacity of the modified MSWI fly ash for Cu(Ⅱ) increased by 2.7, 1.9 and 1.2 times, respectively. Furthermore, it was suggested that the adsorption process of the modified MSWI fly ash can be better simulated by the pseudo-second-order kinetic model, with a maximum adsorption capacity calculated by the Langmuir model of 24.196 mg.g-1. Additionally, the adsorption process is spontaneous,endothermic, and chemisorption-dominated from the thermodynamic studies(Δh and ΔS > 0, ΔG he enhanced adsorption performance of the modified MSWI fly ash for Cu(Ⅱ) may be attributed to electrostatic interaction and chelation effects.

关键词： Ultrasound MSWI fly ash Cu(Ⅱ) Wastewater Adsorption

Saliency-guided meta-hallucinator for few-shot learning

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Science China(Information Sciences) 2024年第10期67卷 189-210页

作者： hongguang ZhANG Chun LIU Jiandong WANG linru MA Piotr KONIUSZ Philip h.S.TORR lin YANG Systems Engineering Institute Academy of Military Sciences Data61 Commonwealth Scientific and Industrial Research Organisation Australian National University Oxford University

Learning novel object concepts from limited samples remains a considerable challenge in deep learning. The main directions for improving the few-shot learning models include(i) designing a stronger backbone,(ii) designing a powerful(dynamic) meta-classifier, and(iii) using a larger pre-training set obtained by generating or hallucinating additional samples from the small scale dataset. In this paper, we focus on item(iii) and present a novel meta-hallucination strategy. Presently, most image generators are based on a generative network(i.e., GAN) that generates new samples from the captured distribution of images. however, such networks require numerous annotated samples for training. In contrast, we propose a novel saliency-based end-to-end meta-hallucinator, where a saliency detector produces foregrounds and backgrounds of support images. Such images are fed into a two-stream network to hallucinate feature samples directly in the feature space by mixing foreground and background feature samples. Then, we propose several novel mixing strategies that improve the quality and diversity of hallucinated feature ***, as not all saliency maps are meaningful or high quality, we further introduce a meta-hallucination controller that decides which foreground feature samples should participate in mixing with backgrounds. To our knowledge, we are the first to leverage saliency detection for few-shot learning. Our proposed network achieves state-of-the-art results on publicly available few-shot image classification and anomaly detection benchmarks, and outperforms competing sample mixing strategies such as the so-called Manifold Mixup.

关键词： few-shot learning saliency detection object recognition anomaly detection computer vision